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Secondary battery

a second battery and battery technology, applied in the field of secondary batteries, can solve the problems of thermal runaway and thermal runaway, and achieve the effect of improving safety and reliability

Active Publication Date: 2012-07-31
KK TOSHIBA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention aims to provide a secondary battery with improved safety and reliability. The invention includes a positive electrode and a negative electrode with a separator interposed between them. The positive electrode has a belt-shaped current collector with tabs protruding from one side edge, while the negative electrode has a belt-shaped current collector with tabs protruding from one side edge. The current collectors have step parts with a deviation of 0.2 mm or more on each side. The invention also includes a spiral-shaped battery with the electrodes and separator rolled up. The technical effect of the invention is to improve the stability and reliability of the secondary battery.

Problems solved by technology

However, in the conventional non-aqueous electrolyte secondary battery, when the temperature inside the battery rises for some reason, thermal contraction occurs in the separator for electrically insulating the positive electrode and negative electrode from each other, whereby the positive and negative electrodes are short-circuited, and the short-circuit current causes further heat generation, leading to thermal runaway, in some cases.
For example, it is known that the internal temperature of a battery rises when overcharging above the rated charge is carried out inadvertently, and depending on the circumstances, there is the possibility of thermal runaway being caused due to thermal contraction of the separator.

Method used

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Examples

Experimental program
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Effect test

example 1

[0084]As shown in FIGS. 5A and 5B, on each of both side edges of the positive electrode 18 in the longitudinal direction thereof, step parts 26 each having a height of 0.2 mm, and deviations were formed at eleven positions.

[0085]On each of both side edges of the negative electrode 20 in the longitudinal direction thereof, step parts 30 each having a height of 0.2 mm, and deviations were formed at eleven positions. The positive electrode 18 and negative electrode 20 were rolled up into a flat shape with the separator 22 interposed between the electrodes. The number of turns when each of the positive and negative electrodes was rolled up was 20.

[0086]As the positive electrode active material, LiCoO2 was used, acetylene black, and carbon black were added thereto as an electric conduction auxiliary agent, polyvinylidene-fluoride was added thereto as a binding agent, predetermined amounts of the above materials were mixed with each other together with a solvent to obtain a paste-like mat...

example 2

[0090]The following external short-circuit test was carried out by using the same secondary battery as example 1. The second battery was brought into the fully-charged state. Thereafter, a resistance of 10 mΩ was connected to the second battery, and the battery was discharged. As a result of this, the battery did not result in thermal runaway. The experiment was repeated three times, which did not result in thermal runaway of the battery. The results are shown in Table 1 below.

example 3

[0091]A plurality of step parts and deviations were formed only on the side edge of the electrode of the side on which the current collection tabs are provided, and the side edge on the opposite side was made a linear side edge without step parts. Other configurations were identical with example 1, and a secondary battery was manufactured. The same overcharge test as example 1 was carried out on this secondary battery, and the battery did not result in thermal runaway. However, in the second experiment, white smoke was emitted from the battery, leading to thermal runaway. In the third experiment, the battery did not result in thermal runaway. The results are shown in Table 1.

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Abstract

An electrode body of a secondary battery is formed by superimposing a positive electrode and a negative electrode upon each other with a belt-shaped separator interposed between the electrodes, and rolling up the positive and negative electrodes and the separator into a spiral shape. At least one side edge of a positive electrode current collector of the positive electrode in the longitudinal direction thereof includes a plurality of step parts discontinuously formed in the longitudinal direction at unequal intervals, and extends at both sides of each step part with a deviation of 0.2 mm or more. At least one side edge of a negative electrode current collector of the negative electrode in the longitudinal direction thereof includes a plurality of step parts discontinuously formed in the longitudinal direction at unequal intervals, and extends on both sides of each step part with a deviation of 0.2 mm or more.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2008-255197, filed Sep. 30, 2008, the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a secondary battery such as a non-aqueous electrolyte secondary battery or the like.[0004]2. Description of the Related Art[0005]In recent years, a secondary battery such as a non-aqueous electrolyte secondary battery or the like attracts attention as a power source of a hybrid electric vehicle or electric storage device for an electric generator that uses natural energy such as sunlight or wind. In general, a non-aqueous electrolyte secondary battery is provided with an exterior member constituted of a metallic container, a laminate film or the like, an electrode body contained in the exterior member together with an electrolyte liquid, ...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H01M4/70H01M6/10H01M2/26H01M10/04H01M10/0587H01M50/538
CPCH01M2/263H01M10/0431H01M4/70Y02E60/10H01M50/538Y02P70/50H01M10/0587H01M10/052H01M50/463
Inventor MORISHIMA, HIDEAKIHIKATA, SEIICHI
Owner KK TOSHIBA